1. Field of the Invention
The present invention generally relates to containers, and more particularly, to an improved hinge for connecting the lid or cover of a container to the base of the container.
2. Description of the Related Art
There is a demand in the market place for improved methods of closing and securably sealing containers. Historically, perishable products such as baked goods and vegetables had to be brought to market and sold quickly before exposure to the atmosphere caused the products to lose their freshness. The advent of plastics resulted in many products being wrapped or packaged in plastic, both in the form of flexible plastic bags and solid plastic containers. The use of plastics has greatly improved the "shelf life" of perishable products for longer periods of time, resulting in a substantial savings.
The use of plastics has also resulted in many food service establishments having open counters of food wherein the individual customer selects his particular portion and fills his own container. These containers are often lightweight and have hinges that make it difficult to securely close the container.
A number of sealable containers are currently available and are typically formed from plastic or other lightweight materials. For example, U.S. Pat. No. 4,753,351 to Guillin discloses a P.V.C. or polystyrene sealable container that includes a base tray and a hinged cover. The food is placed in the tray and the cover is brought into sealed engagement with the base tray to seal the food from the environment. Similarly, U.S. Pat. No. 4,976,370 to Cassel discloses a container and sealing lid formed of plastic such as polypropylene or polyethylene.
While such containers have successfully increased the life of perishable products, the effectiveness of the container is severely limited by the hinge between the base of the container and the lid. Two main difficulties are presented with the typical container hinge. In the first instance, when the hinge is formed by bending the plastic bridging the lid and the base, this area is quickly weakened by such flexing. Repeated flexure results in rapid failure of the plastic thereby separating the cover from its base. This problem has been addressed by making the plastic area forming the hinge of more substantial material. Unfortunately, this solution has brought a second problem to the container art.
When the area bridging the cover and base of a container is fortified by placement of increased areas of thickness, it becomes difficult to close the lid. This is particularly true the first time of closure and is also particularly unfortunate. It is unfortunate because usually, the first closure is when the customer has filled the base with contents, it is most unstable, and the customer rarely has a free hand to assist in closing the container. Secondly, when the area that is formed to be the hinge is made more substantial in order to reduce failure, it becomes biased in the open position. That is, in its natural state the cover tends to remain open and requires additional force to close the container.
There is therefore a great need in the art for a container having a hinge which can be easily closed the first time of closure and which can have multiple flexures without failure.